From patchwork Thu Jun 28 16:40:11 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 10494837 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C99DC601BE for ; Thu, 28 Jun 2018 19:07:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CC41F2A27E for ; Thu, 28 Jun 2018 19:07:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C03CE2A308; Thu, 28 Jun 2018 19:07:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 51A622A27E for ; Thu, 28 Jun 2018 19:07:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933796AbeF1THu (ORCPT ); Thu, 28 Jun 2018 15:07:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:37708 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751981AbeF1TD2 (ORCPT ); Thu, 28 Jun 2018 15:03:28 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0F821ACF8; Thu, 28 Jun 2018 19:03:25 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id F221D1E3C25; Thu, 28 Jun 2018 18:40:31 +0200 (CEST) From: Jan Kara To: linux-audit@redhat.com Cc: Paul Moore , , Al Viro , Richard Guy Briggs , Jan Kara Subject: [PATCH 3/6] audit: Fix possible tagging failures Date: Thu, 28 Jun 2018 18:40:11 +0200 Message-Id: <20180628164014.4925-4-jack@suse.cz> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20180628164014.4925-1-jack@suse.cz> References: <20180628164014.4925-1-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Audit tree code is replacing marks attached to inodes in non-atomic way. Thus fsnotify_find_mark() in tag_chunk() may find a mark that belongs to a chunk that is no longer valid one and will soon be destroyed. Tags added to such chunk will be simply lost. Fix the problem by making sure old mark is marked as going away (through fsnotify_detach_mark()) before dropping mark_mutex and thus in an atomic way wrt tag_chunk(). Note that this does not fix the problem completely as if tag_chunk() finds a mark that is going away, it fails with -ENOENT. But at least the failure is not silent and currently there's no way to search for another fsnotify mark attached to the inode. We'll fix this problem in later patch. Signed-off-by: Jan Kara --- kernel/audit_tree.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index de8d344d91b1..7f9df8c66227 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -278,8 +278,9 @@ static void untag_chunk(struct node *p) list_del_init(&p->list); list_del_rcu(&chunk->hash); spin_unlock(&hash_lock); + fsnotify_detach_mark(entry); mutex_unlock(&entry->group->mark_mutex); - fsnotify_destroy_mark(entry, audit_tree_group); + fsnotify_free_mark(entry); goto out; } @@ -320,8 +321,9 @@ static void untag_chunk(struct node *p) list_for_each_entry(owner, &new->trees, same_root) owner->root = new; spin_unlock(&hash_lock); + fsnotify_detach_mark(entry); mutex_unlock(&entry->group->mark_mutex); - fsnotify_destroy_mark(entry, audit_tree_group); + fsnotify_free_mark(entry); fsnotify_put_mark(&new->mark); /* drop initial reference */ goto out; @@ -364,8 +366,9 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree) if (tree->goner) { spin_unlock(&hash_lock); chunk->dead = 1; + fsnotify_detach_mark(entry); mutex_unlock(&audit_tree_group->mark_mutex); - fsnotify_destroy_mark(entry, audit_tree_group); + fsnotify_free_mark(entry); fsnotify_put_mark(entry); return 0; } @@ -446,10 +449,9 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) if (tree->goner) { spin_unlock(&hash_lock); chunk->dead = 1; + fsnotify_detach_mark(chunk_entry); mutex_unlock(&audit_tree_group->mark_mutex); - - fsnotify_destroy_mark(chunk_entry, audit_tree_group); - + fsnotify_free_mark(chunk_entry); fsnotify_put_mark(chunk_entry); fsnotify_put_mark(old_entry); return 0; @@ -477,8 +479,9 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) list_add(&tree->same_root, &chunk->trees); } spin_unlock(&hash_lock); + fsnotify_detach_mark(old_entry); mutex_unlock(&audit_tree_group->mark_mutex); - fsnotify_destroy_mark(old_entry, audit_tree_group); + fsnotify_free_mark(old_entry); fsnotify_put_mark(chunk_entry); /* drop initial reference */ fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */ return 0;